An electrophoretic display (EPD) is a non-emissive device based on the electrophoresis phenomenon of charged pigment particles suspended in a solvent. The display usually comprises two plates with electrodes placed opposing each other. One of the electrodes is usually transparent. A suspension composed of a colored solvent and charged pigment particles is enclosed between the two plates. When a voltage difference is imposed between the two electrodes, the pigment particles migrate to one side or the other, according to the polarity of the voltage difference. As a result, either the color of the pigment particles or the color of the solvent may be seen at the viewing side.
The two electrode layers of an electrophoretic display are individually connected to a driver so that appropriate voltages may be applied to the electrode layers. For the common electrode to be applied a voltage, a hole is usually drilled through the display panel connected to the common electrode to allow the common electrode to be connected to a driver. Alternatively, as described in US Patent Application Publication No. 2011-0080362, for a display panel attached to a common electrode but separate from a backplane, conductive contact pads are required to allow the common electrode to be connected to a driver. These methods for constructing an electrophoretic display require complex driving circuits and contact points, which lead to added costs.